Poly-v belt power transmission systems are well known in the prior art. Such systems are used extensively in automotive applications. Poly-v belts have a plurality of raised and indented areas which run longitudinally and parallel along the belt. There are three types of poly-v belts sold commercially. These are "K" type, the "J" type and the "L" type. The "K" type poly-v belt is generally used in automotive applications.
The Society for Automotive Engineers (SAE) has developed standard profiles for pulleys which are used for driving "K" type poly-v belts. The standard is designated the J1459 standard. The SAE standard actually specifies two profiles, a "full" profile and "truncated" profile. The latter may be used to minimize the material content and weight of a poly-v pulley while still maintaining suitable power transmission characteristics.
Poly-v pulleys designed for automotive applications are generally made from hot rolled low carbon steel. The pulleys are formed by spin forming processes. Examples of pulleys and the processes by which they are made are shown in U.S. Pat. Nos. 4,551,122 and 4,273,547. Spin forming processes are well suited for making such pulleys because the pulleys can be made light in weight, which is particularly important in automotive applications where reduced rotational inertia is desired to improve fuel economy. Also, spin forming enables making such pulleys quickly and at a lower cost than other methods of manufacture.
Thus there exists a need for a poly-v pulley which is lower in weight than conventional pulleys and which has power transmission qualities comparable or greater than prior designs and which can be produced at a lower cost.